Full-scrap steel is used as raw material for smelting in electric arc furnace. Dephosphorization operation is one of the extremely important process in the smelting process of electric arc furnaces for full-scrap steel. In the process of dephosphorization in the electric arc furnace for full-scrap steel, due to the high melting point of the scrap steel, the temperature of the furnace hearth must be kept high to ensure that the scrap steel is completely melted down, which results in difficulty in carrying out dephosphorization reaction in the molten steel. In order to solve this problem, smelting in conventional electric arc furnaces for full-scrap steel mainly adopts the way of repeatedly slagging, and adopts automatic operation of flowing slag out of the furnace door. However, due to the fact that a previous batch of slag can not be discharged thoroughly prior to forming new dephosphorization slag everytime, the dephosphorization efficiency of slag decreases significantly, and deep dephosphorization of the molten steel is particularly difficult. “Rephosphorization” phenomenon is very serious with the rise of temperature of the molten steel in later period of smelting. Meanwhile iron loss in the molten steel is very large in the process of repeatedly slagging, leading to severe resource waste and significant increase in production costs.
In the smelting process of electric arc furnaces for full-scrap steel, the degassing and decontamination process also can not be ignored. Due to the low carbon content in the molten steel after the scrap steel in the electric arc furnaces for full-scrap steel is melted down, the number of bubbles in the molten steel is obviously insufficient during the decarburization period, which can not deeply remove the [N], [H] and impurities in the molten steel, resulting in the high content of [N], [H] and impurities in the molten steel of electric arc furnaces for full-scrap steel. To compensate for lack of carbon content in molten steel, the way of adding a certain proportion of carbon-containing iron block in the scrap steel is mainly adopted in the conventional smelting of the electric arc furnaces for full-scrap to try to improve the carbon content of molten steel. But because the carbon content in iron block is not high, it is still unable to solve the problem of low carbon content of molten steel, resulting in difficulty in producing clean steel using electric arc furnaces for full-scrap steel.